1. General
This appendix defines the specific provisions regarding the correction of test results for fuel consumption (l/100 km) and CO2 emissions (g/km) as a function of the energy balance for the vehicle batteries.
The corrected values for fuel consumption and CO2 emissions should correspond to a zero energy balance ( ), and are calculated using a correction coefficient determined as defined below.
2. Measurement equipment and instrumentation 2.1. Current transducer
2.1.1. The battery current shall be measured during the tests using a clamp-on or closed type current transducer. The current transducer (i.e. a current sensor without data acquisition equipment) shall have a minimum accuracy of 0.5 per cent of the measured value (in A) or 0.1 per cent of full scale deflection, whichever is smaller.
2.1.2. The current transducer shall be fitted on one of the cables connected directly to the battery. In order to easily measure battery current using external measuring equipment, manufacturers should preferably integrate appropriate, safe and accessible connection points in the vehicle. If this is not feasible, the manufacturer shall support the responsible authority by providing the means to connect a current transducer to the battery cables in the above described manner.
2.1.3. Current transducer output shall be sampled with a minimum frequency of 5 Hz. The measured current shall be integrated over time, yielding the measured value of Q, expressed in ampere-hours (Ah).
2.2. Vehicle on-board data
2.2.1. Alternatively, the battery current shall be determined using vehicle-based data. In order to use this measurement method, the following information shall be accessible from the test vehicle:
(a) Integrated charging balance value since last ignition run in Ah;
(b) Integrated on-board data charging balance value calculated with a minimum sample frequency of 5 Hz;
(c) The charging balance value via an OBD connector as described in SAE J1962.
2.2.2. The accuracy of the vehicle on-board battery charging and discharging data shall be demonstrated by the manufacturer to the responsible authority.
The manufacturer may create a battery monitoring vehicle family to prove that the vehicle on-board battery charging and discharging data are correct.
The accuracy of the data shall be demonstrated on a representative vehicle.
The following family criteria shall be valid:
(a) Identical combustion processes;
(b) Identical charge and/or recuperation strategy (software battery data module);
(c) On-board data availability;
(d) Identical charging balance measured by battery data module;
(e) Identical on-board charging balance simulation.
3. Measurement procedure 3.1. External battery charging
Before the preconditioning test cycle, the battery shall be fully charged. The battery shall not be charged again before the official testing according to paragraph 1.2.6.2. of this annex.
3.2. Measurement of the battery current shall start at the same time as the test starts and shall end immediately after the vehicle has driven the complete driving cycle.
3.3. The electricity balance, Q, measured in the electric power supply system, is used as a measure of the difference in the REESS energy content at the end of the cycle compared to the beginning of the cycle. The electricity balance is to be determined for the total WLTC for the applicable vehicle class.
3.4. Separate values of shall be logged over the cycle phases required to be driven for the applicable vehicle class.
3.5. and test results shall be corrected as a function of the REESS energy balance RCB.
3.6. The test results shall be the uncorrected measured values of and in case any of the following applies:
(a) The manufacturer can prove that there is no relation between the energy balance and fuel consumption;
(b) as calculated from the test result corresponds to REESS charging;
(c) as calculated from the test result corresponds to REESS charging and discharging. , expressed as a percentage of the energy content of the fuel consumed over the cycle, is calculated in the equation below:
where:
is the change in the REESS energy content, per cent;
is the nominal REESS voltage, V;
RCB is REESS charging balance over the whole cycle, Ah;
is the energy content of the consumed fuel, MJ.
is lower than the RCB correction criteria, according to the equation below and Table 1:
Table A6.App2/1 RCB correction criteria
Cycle
WLTC city(low + medium)
WLTC (low + medium + high)
WLTC(low + medium + high + extra high)
RCB correction criteria (%)
1.5 1 0.5
4. Correction method
4.1. To apply the correction function, the electric power to the battery must be calculated from the measured current and the nominal voltage value for each phase of the WLTC test:
where:
is the change in the electrical REESS energy content of phase i, MJ;
is the nominal REESS voltage, V;
is the electric current in phase (i), A;
is the time at the end of phase (i), seconds (s).
4.2. For correction of fuel consumption, l/100 km, and CO2 emissions, g/km, combustion process-dependent Willans factors from Table A6.App2/2 (paragraph 4.8. below) shall be used.
4.3. The resulting fuel consumption difference of the engine for each WLTC phase due to load behaviour of the alternator for charging a battery shall be calculated as shown below:
where:
is the resulting fuel consumption difference of phase (i), l;
is the change in the electrical REESS energy content of phase (i), MJ;
is the efficiency of the alternator;
is the combustion process specific Willans factor as defined in Table A6.App2/2.
4.4. The resulting CO2 emissions difference of the engine for each WLTC phase due to load behaviour of the alternator for charging a battery shall be calculated as shown below:
where:
is the resulting CO2-emission difference of phase (i), g;
is the change in the electrical REESS energy content of phase (i), MJ;
is the efficiency of the alternator;
is the combustion process specific Willans factor as defined in Table A6.App2/2.
4.5. For this specific calculation, a fixed electric power supply system alternator efficiency shall be used:
4.6. The consumption difference of the engine for the WLTC test is the sum over the (i) single phases as shown below:
where:
is the change in consumption over the whole cycle, l.
4.7. The CO2 emissions difference of the engine for the WLTC test is the sum over the (i) single phases as shown below:
where:
is the change in CO2-emission over the whole cycle, g.
4.8. For correction of the fuel consumption, l/100 km, and CO2 emission, g/km, the Willans factors in Table A6.App2/2 shall be used.
Table A6.App2/2 Willans factors
Naturally aspirated
Pressure charged
Positive ignition Gasoline (E0) l/kWh 0.264 0.28
gCO2/kWh 630 668
Gasoline (E5) l/kWh 0.268 0.284
gCO2/kWh 628 666
CNG (G20) m³/kWh 0.259 0.275
gCO2/kWh 465 493
LPG l/kWh 0.342 0.363
gCO2/kWh 557 591
E85 l/kWh 0.367 0.389
gCO2/kWh 608 645
Compression ignition
Diesel (B0) l/kWh 0.22 0.22
gCO2/kWh 581 581
Diesel (B5) l/kWh 0.22 0.22
gCO2/kWh 581 581
Annex 7
Calculations
1. General requirements
1.1. Calculations related specifically to hybrid and pure electric vehicles are described in Annex 8.
1.2. The calculations described in this annex shall be used for vehicles using combustion engines.
1.3.. The final test results shall be rounded in one step to the number of places to the right of the decimal point indicated by the applicable emission standard plus one additional significant figure. Intermediate steps in the calculations shall not be rounded.
1.4. The NOx correction factor, , shall be rounded to 2 decimal places.
1.5. The dilution factor, , shall be rounded to 2 decimal places.
1.6. For information not related to standards, good engineering judgement shall be used.
2. Determination of diluted exhaust gas volume
2.1. Diluted exhaust gas volume calculation for a variable dilution device capable of operating at a constant or variable flow rate.
2.1.1. The parameters showing the volumetric flow shall be recorded continuously.
The total volume shall be recorded for the duration of the test.
2.2. Volume calculation for a variable dilution device using a positive displacement pump
2.2.1. The volume shall be calculated using the following equation:
(1) where:
is the volume of the diluted gas, in litres per test (prior to correction);
is the volume of gas delivered by the positive displacement pump in testing conditions, N-1;
is the number of revolutions per test.
2.2.1.1. Correcting the volume to standard conditions
2.2.1.1.1. The diluted exhaust gas volume, V, shall be corrected to standard conditions according to the following equation:
(2) where:
is the test room barometric pressure, kPa;
is the vacuum at the inlet to the positive displacement pump relative to the ambient barometric pressure, kPa;
is the average temperature of the diluted exhaust gas entering the positive displacement pump during the test, Kelvin (K).
3. Mass emissions
3.1. General requirements
3.1.1. Assuming no compressibility effects, all gases involved in the engine intake/combustion/exhaust process can be considered to be ideal according to Avogadro’s hypothesis.
3.1.2. The mass of gaseous compounds emitted by the vehicle during the test shall be determined by obtaining the product of the volumetric concentration of the gas in question and the volume of the diluted exhaust gas with due regard for the following densities under the reference conditions of 273.15 K and 101.325 kPa:
Carbon monoxide (CO) g/l
Carbon dioxide (CO2) g/l
Hydrocarbons:
for petrol (E0) (C1H1.85) g/1
for petrol (E5) (C1H1.89O0.016) g/1
for diesel (B0) (C1Hl.86) g/1
for diesel (B5) (C1Hl.86O0.005) g/1
for LPG (C1H2.525) g/l
for NG/biomethane (CH4) g/l
for ethanol (E85) (C1H2,74O0.385) g/l
Nitrogen oxides (NOx) g/1
Nitrogen dioxide (NO2) g/1
Nitrous oxide (N2O) g/1
The density for NMHC mass calculations shall be equal to that of total hydrocarbons at 273.15 K and 101.325 kPa and is fuel-dependent.
3.2. Mass emissions calculation
3.2.1. Mass emissions of gaseous compounds shall be calculated using the following equation:
(3) where:
is the mass emissions of compound (i), g/km;
is the volume of the diluted exhaust gas expressed in litres per test and corrected to standard conditions (273.15 K and 101.325 kPa);
is the density of compound (i) in grams per litre at normal temperature and pressure (273.15 K and 101.325 kPa);
is a humidity correction factor applicable only to the mass emissions of oxides of nitrogen (NO2 and NOx);
is the concentration of compound (i) in the diluted exhaust gas expressed in ppm and corrected by the amount of the compound (i) contained in the dilution air;
is the distance driven over the corresponding WLTC, km.
3.2.1.1. The concentration of a gaseous compound in the diluted exhaust gas shall be corrected by the amount of the gaseous compound in the dilution air as follows:
(4) where:
is the concentration of gaseous compound (i) in the diluted exhaust gas corrected by the amount of gaseous compound (i) contained in the dilution air, ppm;
is the measured concentration of gaseous compound (i) in the diluted exhaust gas, ppm;
is the concentration of gaseous compound (i) in the air used for dilution, ppm;
is the dilution factor.
3.2.1.1.1. The dilution factor, , is calculated as follows:
for petrol (E0, E5 and B0) (5a)
for diesel (B5) (5b)
for LPG (5c)
for NG/biomethane (5d)
for ethanol (E85) (5e)
3.2.1.1.2. General equation for the dilution factor (DF) for each reference fuel with an average composition of CxHyOz is:
(6)
where:
is the concentration of CO2 in the diluted exhaust gas contained in the sampling bag, per cent volume;
is the concentration of HC in the diluted exhaust gas contained in the sampling bag, ppm carbon equivalent;
is the concentration of CO in the diluted exhaust gas contained in the sampling bag, ppm.
3.2.1.1.3. Methane measurement
3.2.1.1.3.1. For methane measurement using a GC-FID, NMHC is calculated as follows:
(7) where:
is the corrected concentration of NMHC in the diluted exhaust gas, ppm carbon equivalent;
is the concentration of THC in the diluted exhaust gas, ppm carbon equivalent and corrected by the amount of THC contained in the dilution air;
is the concentration of CH4 in the diluted exhaust gas, ppm carbon equivalent and corrected by the amount of CH4 contained in the dilution air;
is the FID response factor to methane as defined in paragraph 5.4.3.2. of Annex5.
3.2.1.1.3.2. For methane measurement using a NMC-FID, the calculation of NMHC depends on the calibration gas/method used for the zero/calibration adjustment.
The FID used for the THC measurement (without NMC) shall be calibrated with propane/air in the normal manner.
For the calibration of the FID in series with NMC, the following methods are permitted :
(a) The calibration gas consisting of propane/air bypasses the NMC;
(b) The calibration gas consisting of methane/air passes through the NMC.
It is strongly recommended to calibrate the methane FID with methane/air through the NMC.
In case (a), the concentration of CH4 and NMHC shall be calculated as follows:
(8) (9) In case (b), the concentration of CH4 and NMHC shall be calculated as follows:
(10) (11) where:
is the HC concentration with sample gas flowing through the NMC, ppm C;
is the HC concentration with sample gas bypassing the NMC, ppm C;
is the methane response factor as determined per paragraph 5.4.3.2 of Annex 5;
is the methane efficiency as determined per paragraph 3.2.1.1.3.3.1. below;
is the ethane efficiency as determined per paragraph 3.2.1.1.3.3.2. below.
If < 1.05, it may be omitted in equations 8, 10 and 11.
3.2.1.1.3.3. Conversion efficiencies of the non-methane cutter (NMC)
The NMC is used for the removal of the non-methane hydrocarbons from the sample gas by oxidizing all hydrocarbons except methane. Ideally, the conversion for methane is 0 per cent, and for the other hydrocarbons represented by ethane is 100 per cent. For the accurate measurement of NMHC, the two efficiencies shall be determined and used for the calculation of the NMHC emission.
3.2.1.1.3.3.1. Methane conversion efficiency
The methane/air calibration gas shall be flowed to the FID through the NMC and bypassing the NMC and the two concentrations recorded. The efficiency shall be determined as follows:
(12) where:
is the HC concentration with CH4 flowing through the NMC, ppm C;
is the HC concentration with CH4 bypassing the NMC, ppm C.
3.2.1.1.3.3.2. Ethane conversion efficiency
The ethane/air calibration gas shall be flowed to the FID through the NMC and bypassing the NMC and the two concentrations recorded. The efficiency shall be determined as follows:
(13) where:
is the HC concentration with C2H6 flowing through the NMC, ppm C;
is the HC concentration with C2H6 bypassing the NMC in ppm C.
If the ethane conversion efficiency of the NMC is 0.98 or above, EE shall be set to 1 for any subsequent calculation.
3.2.1.1.3.4. If the methane FID is calibrated through the cutter, then EM is 0.
Equation (10) from above becomes:
(14)
Equation (11) from above becomes:
(15) The density used for NMHC mass calculations shall be equal to that of total hydrocarbons at 273.15 K and 101.325 kPa and is fuel-dependent.
3.2.1.1.4. Flow weighted average concentration calculation
The following calculation method shall only be applied for CVS systems that are not equipped with a heat exchanger or for CVS systems with a heat exchanger that do not comply with paragraph 3.3.5.1. of Annex 5.
When the CVS flow rate over the test varies more than ±3 per cent of the average flow rate, a flow weighted average shall be used for all continuous diluted measurements including PN:
(16) where:
is the flow-weighted average concentration;
is the CVS flow rate at time , m³/min;
is the concentration at time , ppm;
sampling interval, seconds (s);
total CVS volume, m³.
3.2.1.2. Calculation of the NOx humidity correction factor
In order to correct the influence of humidity on the results of oxides of nitrogen, the following calculations apply:
(17) where:
(18) and:
is the absolute humidity, grams of water per kilogram of dry air;
is the relative humidity of the ambient air, per cent;
is the saturation vapour pressure at ambient temperature, kPa;
is the atmospheric pressure in the room, kPa.
The KH factor shall be calculated for each phase of the test cycle.
The ambient temperature and relative humidity shall be defined as the average of the continuously measured values during each phase.
3.2.1.3. Determination of NO2 concentration from NO and NOx
NO2 is determined by the difference between NOx concentration from the bag corrected for dilution air concentration and NO concentration from continuous measurement corrected for dilution air concentration
3.2.1.3.1. NO concentrations
3.2.1.3.1.1. NO concentrations shall be calculated from the integrated NO analyser reading, corrected for varying flow if necessary.
3.2.1.3.1.2. The average NO concentration is calculated as follows:
(19) where:
is the integral of the recording of the modal NO analyser over the test (t2-t1);
is the concentration of NO measured in the diluted exhaust, ppm;
3.2.1.3.1.3. Dilution air concentration of NO is determined from the dilution air bag.
Correction is carried out according to paragraph 3.2.1.1. of this annex.
3.2.1.3.2. NO2 concentrations
3.2.1.3.2.1. Determination NO2 concentration from direct diluted measurement
3.2.1.3.2.2. NO2 concentrations shall be calculated from the integrated NO2 analyser reading, corrected for varying flow if necessary.
3.2.1.3.2.3. The average NO2 concentration is calculated as follows:
(20) where:
is the integral of the recording of the modal NO2 analyser over the test (t2-t1);
is the concentration of NO2 measured in the diluted exhaust, ppm.
3.2.1.3.2.4. Dilution air concentration of NO2 is determined from the dilution air bags.
Correction is carried out according to paragraph 3.2.1.1. of this annex.
3.2.2. Determination of the HC mass emissions from compression-ignition engines 3.2.2.1. To calculate HC mass emission for compression-ignition engines, the average
HC concentration is calculated as follows:
(21) where:
is the integral of the recording of the heated FID over the test (t1 to t2);
is the concentration of HC measured in the diluted exhaust in ppm of and is substituted for in all relevant equations.
3.2.2.1.1. Dilution air concentration of HC shall be determined from the dilution air bags. Correction shall be carried out according to paragraph 3.2.1.1. of this annex.
3.2.3. CO2 calculation for individual vehicles in a CO2 vehicle family
3.2.3.1. CO2 emissions without using the interpolation method
If the road load and emissions have been not been measured on test vehicle L in addition to test vehicle H, the value , as calculated in paragraph 3.2.1.
above, shall be attributed to all individual vehicles in the CO2 vehicle family and the CO2 interpolation method is not applicable.
3.2.3.2. CO2 emissions using the interpolation method
If the road load and emissions are measured on test vehicles L and H, the CO2 emission for each individual vehicle in the CO2 vehicle family may be calculated according to the CO2 interpolation method outlined in the following paragraphs.
3.2.3.2.1. Determination of CO2 emissions test vehicles L and H
The mass of CO2 emissions, , for test vehicles L and H shall be determined according to the calculation in paragraph 3.2.1. above for the individual cycle phases p of the WLTC applicable for the class of the CO2 vehicle family. and are referred to as and respectively.
3.2.3.2.2. Road load calculation for an individual vehicle 3.2.3.2.2.1. Mass of the individual vehicle
The selected test masses TML and TMH as determined in paragraph 4.2.1.3.1.
of Annex 4 shall be used as input for the interpolation method.
The mass of the optional equipment shall be calculated for the individual vehicle according to the following equation:
(22) where:
is the difference in mass between the individual vehicle and ; is the mass of an individual option i on the vehicle ( is positive for
an option that adds mass with respect to and vice versa);
is the number of options that are different between the individual vehicle and test vehicle L.
The value of for test vehicle H shall be the same as the difference between and .
The mass of the individual vehicle is calculated according to the following equation:
(23) where is the mass of the individual vehicle used as input for the CO2interpolation method.
If the same test mass was used for test vehicles L and H, the value of shall be set to for the interpolation method.
3.2.3.2.2.2. Rolling resistance of the individual vehicle
According to paragraph 4.2.2.1. of Annex 4, the actual rolling resistance values for the selected tyres on test vehicle L, RRL, and test vehicle H, RRH,
According to paragraph 4.2.2.1. of Annex 4, the actual rolling resistance values for the selected tyres on test vehicle L, RRL, and test vehicle H, RRH,